<head>
    <link href="https://cdn.bootcss.com/bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet">
    <script src="https://cdn.bootcss.com/jquery/3.2.1/jquery.min.js"></script>
    <script src="https://cdn.bootcss.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>
      <style>
  textarea, button {display: block}
</style>
</head>
<body>
  <div class="container">
    <form method="post" class="col-md-4 col-md-offset-4">
      <textarea rows="10" name="ids" class="form-control"></textarea>
      <button type="submit" class="btn btn-default">Submit</button>
    </form>
  </div>
  
  <!--

  -->
</body>